Our general recommendation is to tip moderately – in accordance with the level and quality of service provided. The following guidelines are generally accepted practice (per person): Safari guide(s) – US $10 per day; Cook 7 US$, Camp staff – US $3 – $5 per day, as a pooled tip to be shared among the housekeepers, waiters, bartender, etc. For porters and waiters at hotels and for taxi drivers in cities, the customary tip is approximately 1 US$. (Tipping in US$1 bills for porters and waiters is greatly appreciated). The traditional gratuity to safari guides or camp staff is not included in the cost of your tour, but is completely discretionary. Beware of unscrupulous people who try to extort extra payment from unwary passengers just for shuffling their bags around.
Please see here regarding tipping on Kilimanjaro climbs